Noise excited resonance apparatus

ABSTRACT

Noise excited radio frequency spectrometers are disclosed wherein resonance of a sample of matter disposed in a polarizing magnetic field is excited by applying noise energy to the sample to excite a spectrum of resonance lines within the sample under analysis. In one embodiment, a sample of the exciting noise is Fourier transformed and a sample of the resultant noise excited spectrum of the sample is similarly Fourier transformed and the two Fourier transformed functions are multiplied to derive a resonance spectrum of the sample under analysis. In another embodiment, a sample of the resonance exciting noise signal is cross-correlated with a sample of the noise excited resonance signal derived from the sample to obtain a cross-correlation function which is Fourier transformed to obtain a resonance line spectrum of the sample under analysis.

United States Patent n91 Ernst 1 NOISE EXCITED RESONANCE APPARATUS [75]-lnventor: Richard R. Ernst, Winterthur, Switzerland Assignee:

Filed:

App]. No.:

Varian Associates, Palo Alto, Calif.

May 28, 1970 [56] References Cited UNITED STATES PATENTS Varian ..324/.5Nelson ..324/.5

OTHER PUBLICATIONS Jan. 16, 1973 Noise excited radio frequencyspectrometers are disclosed wherein resonance of a sample of matterdisposed in a polarizing magnetic field is excited by applying noiseenergy to the sample to excite a spectrum of resonance lines within thesample under analysis. In one embodiment, a sample of the exciting noiseis Fourier transformed and a sample of the resultant noise excitedspectrum of the sample is similarly Fourier transformed and the twoFourier transformed functions are multiplied to derive a resonancespectrum of the sample under analysis. In another embodiment, a sampleof the resonance exciting noise signal is cross-correlated with a sampleof the noise excited resonance signal derived from the sample to obtaina cross-correlation function which is Fourier transformed to obtain aresonance line spectrum of the sample under analysis.

ABSTRACT Hewlett-Packard Journal, September 1967, pp. 7 H 18-20.

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45 i I 44 I Ml f NS AUDIO PHASE MODULATOR OSCILLATOR I 8 SHIFTER R F 9 VPHASE R.F. TRANISRM'TTER MODULATOR PROBE I AMPLIFIER Q- $(t/ We) 9 HOAUDIO SYNCHRONIZER T AMPLIFIER I ADDRESS DETECTOR STORAGE LIJDARIITIIIIIPIATETIC g I INVENTOR. EIEIII IP Q I I I R RIcIIARII ERIIsISEQUENCE RECORDER 7M7 ATTORNEY NOISE EXCITED RESONANCE APPARATUSDESCRIPTION OF THE PRIOR ART Heretofore, noise excited resonance radiofrequency spectrometers have been proposed wherein a band of radiofrequency noise was applied to a sample disposed in a polarizingmagnetic field to excite simultaneous resonance of a plurality ofresonance lines within the sample. The composite noise excited resonancesignal was then picked up and recorded. The recorded signal was Fouriertransformed (analyzed) to derive the separate Fourier frequencycomponents of the resonance spectrum of the sample under analysis. Sucha spectrometer is disclosed and claimed in U.S. Pat. No. 3,287,629issued Nov. 22, 1966 and assigned to the same assignee as the presentinvention. The output spectrum from this prior art spectrometercomprised a power spectrum of the sample under analysis. Such a powerspectrum comprises a combination of both the dispersion and absorptionmodes of resonance and -therefore neither mode was separatelyobservable.

Sometimes it is desired to observe either the dispersion or theabsorption mode resonance.

In another prior art spectrometer, noise energy was applied to a sampleof gyromagnetic bodies disposed in a polarizing magnetic field tosimultaneously excite a resonance line spectrum of the sample underanalysis. The noise energy used to excite resonance of the sample wasderived by means of long repetitive pseudorandom binary sequence whichwas used to phase modulate an RF-transmitter to derive an RF spectrum ofradio frequency noise energy having a spectral density following a (sinx/x) distribution. The resultant noise excited composite resonancesignal emanating from the sample was sampled in a multitude of of timedisplaced intervals in synchronism with binary sequence of thepseudorandom binary sequence used to derive the noise excitation. Oneach repetitive cycle of the pseudorandom binary sequence, the resultantresonance signal was sampled at the same successive time displacedintervals and the resonance signal amplitude at each of the timedisplaced sampling points was stored in a corresponding channel of amemory such that the information for successive binary sequences wasaccumulated in each of a number of the channels in the memory to obtaina time averaged composite resonance signal which was then Fouriertransformed to derive the separate Fourier resonance line components ofthe sample under analysis; Due to the synchronization of the samplingpoints of the resonance signal with the pseudorandom binary sequenceemployed to excite the sample, either the dispersive or absorption moderesonance line components could be derived from the Fourier transformedresonance signals. Such a radio frequency spectrometer is disclosed andclaimed in copending U.S. application Ser. No. 847,859 filed Aug. 6,I969, now U.S. Pat. No. 3,581 ,19 l and assigned to the same assignee asthe present invention. In this prior spectrometer, the Fourier analysiswas performed by means of a Fourier transform computer and the computerwas programmed to take advantage of the fact that the Fourier transformfor the. pseudorandom noise excitation was precisely known and takeninto account in the Fourier transform program of the computer.

SUMMARY OF THE PRESENT INVENTION The principal object of the presentinvention is the provision of improved noise excited resonance methodand apparatus.

One feature of the present invention is the provision, in a noiseexcited resonance apparatus, of a means for correlating the resonanceexciting noise spectrum with the noise excited resonance line spectrumderived from the sample under analysis to obtain a cross-correlationfunction, and means for Fourier analyzing the crosscorrelation functionto obtain a resonance line spectrum of the sample under analysis.

Another feature of the present invention is the provision in a noiseexcited resonance apparatus, of means for Fourier transforming a sampleof the resonance exciting noise energy to derive an exciting noisetransform function and means for Fourier transforming the noise excitedresonance signal emanating from the sample to derive a resonance signaltransform function, and means for complex multiplying the resonanceexciting noise transform function by the resonance transform function ofthe sample to obtain a resonance spectrum of the sample under analysis.

Other features and advantages of the present invention will becomeapparent upon a perusal of the following specification taken inconnection with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic block diagram ofa noise excited resonance spectrometer incorporating features of thepresent invention,

FIG. 2 is a schematic circuit diagram of a portion of the structure ofFIG. I delineated by line 2-2,

FIG. 3 is a schematic block diagram of an alternative spectrometer tothat of FIG. I,

FIG. 4 is a schematic block diagram of an alternative spectrometerincorporating features of the present invention,

FIG. 5 is a schematic block diagram of a radio frequency spectrometerincorporating features of the present invention, and

FIG. 6 is a schematic flow diagram, in block diagram form, depicting theprogram and functions performed in the computer of the spectrometer ofFIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, thereis shown a gyromagnetic resonance radio frequency spectrometer lincorporating features of the present invention. The spectrometerincludes a probe structure 2 for immersing a sample of gyromagneticresonance material, to be analyzed in a polarizing magnetic field, H,,.The probe structure includes conventional resonance circuits disposed inradio frequency energy exchanging relation with the sample, suchcircuits being decoupled from each other.

A radio frequency transmitter 3 produces radio frequency energy at afrequency f disposed at one end of the spectrum of the sample to beexcited. The transmitter supplies the energy to the probe 2 via a phasemodulator 4 which is arranged to modulate the phase of the transmittersignal by at intervals as determined by an input signal derived from arandom binary sequence generator 5. The phase modulated RF energy fed tothe probe 2 excites a resonance circuit within the probe 2 to produce aradio frequency magnetic field coupled to the sample with the magneticvector of the RF field having a strong component at right angles to thepolarizing magnetic field vector H The random binary sequence generatorcan produce a completely random binary sequence that is non-repetitiveor it can be designed to produce a pseudorandom binary sequence, suchpseudorandom binary sequence comprising a relatively long sequence ofbinary outputs, i.e., 66000 bits during a sequence, which are randomwithin the sequence and such sequence being repetitive. In the casewhere the random binary sequence is completely random, i.e.,non-repetitive, with arbitrary switching times, the phase modulator 4combined with the binary random sequence generator 5 constitutes a whitenoise source producing a wideband of RF energy uniformly distributedover the expected bandwidth of the spectrum of the sample to be excited.In the case where the random binary sequence is pseudorandom, i.e.,repetitive, with switching times corresponding to multiples of the basicstep length RF energy applied to the sample will have an envelope, as afunction of frequency, which is a (sin x/x) function, with X 1r(;- f )r.The first mode has a bandwidth BW of 2/1- where r is the time of a basicstep length in the sequence. The basic step length r is illustrated inwaveform (b) of FIG. 1 which waveform constitutes the binary output ofthe sequence 5 and r constitutes the minimum time between successivephase shifts, such time 1' being illustrated in waveform FIG. 1(b) as(t, t The total time T for each pseudorandom sequence is r N, where N isthe total number of basic step lengths in the pseudorandom sequence. Ina typical example, the pseudorandom sequence is one second long andcontains 65,535 step lengths. At the end of the pseudorandom binarysequence, the sequence repeats itself.

The spectral lines of the transmitted signal will have a frequencyseparation AF l/r. Thus, for the case previously mentioned, thefrequency separation of the Fourier components in the pseudorandom noiseis one Hz and the bandwidth is 131,070 hertz. Typically, only one halfof the total available bandwidth is to be employed by positioning f, toone end of the spectrum of the sample to be excited, therefore, theavailable bandwidth is 65,535 Hz which is typically more than adequateto cover the spectrum of proton samples and is also adequate to coverthe spectrum of most fluorine compounds.

The phase modulated transmitter signal is applied to the probe 2 forsimultaneously exciting the various spectral lines of the sample underanalysis to produce a composite resonance signal having a time-varyingenvelope. The composite resonance signal is received in radio frequencyamplifier 6 and amplified and fed to one input of a radio frequencyphase sensitive detector 7 where it is phased detected against areference signal derived from the radio frequency transmitter 3 at thecarrier frequency f,,. A phase shifter 8 is provided for adjusting thephase of the reference signal, if desired.

The output of the radio frequency phase detector 7 is a compositeresonance signal having a time varying envelope, such signal having beentransformed to the audio frequency range via the phase detector 7. Theaudio output of phase sensitive detector 7v (1) is amplified in an audiofrequency amplifier 9 and fed to one input of a correlation coefficientdetermining unit 11 for cross-correlation with a sample of the audiofrequency random binary output of sequence generator 5 which correspondsto the noise exciting function S(t) applied to the sample for noiseexcitation of resonance therein. As used herein, the noise excitingfunction shall be defined as S(t) and the noise excited response in thesample under analysis shall be defined as V(t) and the correlationcoefficient determining unit 11 correlates the noise exciting functionS(t) with the noise excited response V(t) to derive a cross-correlationfunction R (1').

From the theory of linear systems it is known that a linear timeindependent system can be characterized by the response to a noiseperturbation with a frequency independent power spectral densityfunction W,,, (I), usually called white random noise. Thecross-correlation function R,,. (r) of the perturbation S(t) and theresponse V(t) is proportional to the system impulse response h(r) whichis the Fourier transform of the transfer function Y(f) with The bardenotes an ensemble average which, for an ergodic random process S(t),is equivalent to a time average. It is assumed that S(t) has a powerspectral density normalized to W (f) l.

The systems of magnetic resonance, nuclear or electronic spin systems,are non-linear systems in general. Such systems are not uniquelycharacterized by equation (1). However, it has been shown that Gaussianrandom noise with frequency independent power spectral density still isa most appropriate means to characterize non-linear systems. Here, incontrast the linear systems, the probability distribution of the randomnoise becomes important. It is possible to represent the response of anon-linear system to a Gaussian random input as an expansion instochastically orthogonal Hermite polynomials, the different termsrepresent the linear, quadratic, cubic, etc. responses of a non-linearsystem. The linear term is equivalent to equation 1).

The correlation coefficient determining unit 11 may comprise a digitalcomputer or may comprise an analog correlator with delays, multipliers,and storage elements as shown in FIG. 2 for solving equation l Thecross-correlation function output of correlator 11 is fed to the inputof a multi-channel storage and adder 12 wherein it is time averaged andthe output of the multi-channel storage and adder 12 is Fouriertransformed by a Fourier transformer 13, such as a Fourier transformcomputer such as a Varian Data machine computer Model 620 i to producean output spectrum of the sample under analysis which is fed to arecorder 14 for recording as a function of frequency of time derivedfrom the Fourier transformer 13.

Referring now to FIG. 2, the correlator 11 utilizing the analog elementsis disclosed in greater detail. The correlator 11 includes a first inputterminal 16 to which either the exciting noise signal S(t) or the noiseexcited response signal V(t) is applied. A second input terminal 17 hasthe other signal applied thereto, namely,

the noise excited response V(t) or the noise exciting signal S(t),respectively. The input which is applied to input terminal 16 is fed toone input of a first multiplier 18 wherein it is multiplied with theother input signal applied to input terminal 17 to derive an outputR,,,(-ro) =R,,,(o) which is fed to an input of an integrator 19comprising series resistor 21 and shunt capacitor 22. Shunt capacitor 22serves as a storage element and the integrated output signal appears onan output terminal 23.

A first delay element 24 delays a portion of one of the input signalsrelative to the other by a time interval'r, The delayed output of delay24 is fed to one input of a second multiplier 25 wherein it ismultiplied with a sample of the second undelayed input signal V(t) toderive a second cross-correlation output component R,,,, (1-,) appearingacross the storage capacitor 22 of a second integrator 19. The output ofthe first delay 24 is also fed to a second delay 26 which further delaysthe noise exciting signal S(t) so the total delay is nowr The output ofdelay 26 is fed to one input of a third multiplier 27 for multiplicationwith an undelayed sample of the noise excited response signal V(t) toderive a third cross-correlation output component R,.,,('r Thus, in thecorrelator 11, the noise excited resonance response V(t) is successivelymultiplied with a successively delayed portion of the noise excitingsignal S(t) and the output, which forms the cross-correlation componentappears across a succession of storage capacitors 22, there being amultitude of successive delay units and multipliers to derive amultitude of cross-correlations outputs. Should all the delay units havethe same delay timerthen 'r, nr. The outputs are integrated across thestorage capacitors 22 to provide a time average of the cross-correlationfunctions. The time averaged components are then Fourier analyzed byFourier transformer I3 to produce the output resonance line spectrum. Asan alternative to the use of a multitude of delay units, multiplierunits, and integrators, a single delay and a single multiplier may beemployed on a time share basis with the successively derived outputsignals being fed to a multi-channel storage and adder which stores therespective outputs in successive channels for subsequent Fourieranalysis.

Referring again to FIG. 1, in the case that the random binary sequencegenerator 5 is a pseudorandom binary sequence generator producing arandom sequence which repeats itself, the output of the audio frequencyamplifier 9 may be fed to a multi'channel storage and adder unit whichsamples the audio frequency noise response V(t) at a multitude of timedisplaced points and stores the sampled information in respectivechannels of the multi-channel storage and adder, such storage and adderbeing synchronized with the basic unit step rate and cycle of thepseudorandom binary sequence generator such that each repetitive noiseexcited output V(t) corresponding to each cycle of the pseudorandomsequence generator is sampled at the same time displaced intervals withcorresponding sampled signal amplitudes being accumulated in the samerespective channels of the multi-channel storage and adder for obtaininga time average of the noise excited resonance response V(t).

The time averaged response V(t) may then be fed out of the multi-channelstorage and adder to the correlation coefficient determining unit 11 forcomparison with the noise exciting response S(t) corresponding to asingle cycle of the pseudorandom binary sequence, since this excitingresponse will be the identical for each cycle of the pseudorandom binarysequence. The correlated output is Fourier transformed by transformer 13to produce the time averaged output resonance line spectrum.

Referringnow to FIG. 3, there is shown an alternative radio frequencyspectrometer 31 incorporating features of the present invention. Thespectrometer 31 of FIG. 3 is essentially the same as that previouslydescribed with regard to FIG. I with the exception that the spectrum ofnoise exciting energy S(t) applied to the probe 2 is applied by means offield modulation of the polarizing magnetic field. More specifically,the random binary sequence produced at the output of the binarysequence, generator 5 has a waveform as depicted by waveform (a) of FIG.3 and this binary sequence output is fed to a differentiator 32 toproduce relatively short pulses as shown by waveform (b) of FIG. 3, suchpulses having a pulse duration t and intensity II which is eitherpositive or negative in sign depending upon whether the output ofdifferentiator 32 is positive or negative. The output pulse of thedifferentiator 32 are fed to a field modulator 13 which modulates themagnetic polarizing field H, with the pulse I-I, derived from pulsefield modulator 33. In the case of gyromagnetic resonance, each pulse ofduration t and intensity II is proportioned to produce phase reversal ofthe processing gyromagnetic bodies in the polarizing magnetic field H Inother words, the phase modulation type of noise source as utilized inthe spectrometer 1 of FIG. 1 can be shown to be equivalent to the fieldmodulation noise source of FIG. 3 when the following relation isfulfilled:

'yI-I,,t'='n' Eq.(2) where y is the gyromagnetic ratio, H, is theamplitude of the magnetic field modulation and t' is the length of thepulses in the pulse sequence of a waveform (b). Additionally, it isnecessary that t be much, much smaller than 1-, where 1' is the basicunit step length of the binary sequence.

The advantage of the field modulation, as shown in the spectrometer 31of FIG. 3, is that the probe structure and RF amplifier 6 can besimplified since there is no direct coupling of RF energy from thetransmitter into the input of the receiver 6 via the probe 2 when thetransmitter frequence f is displaced from the spectral range of interestof the sample under analysis. This avoids undersired overloading andcoupling of unwanted signals into the input amplifier circuits within RFamplifier 6.

Referring now to FIG. 4, there is shown an altemative RF spectrometer 36incorporating features of the present invention. Spectrometer 36 issubstantially the same as the previously described with regard to FIGS.1 and 3 with the exception that the noise energy S(t) employed to excitethe resonance response V(t) is crosscorrelated with the noise resonanceresponse V(t) by Fourier transforming the noise energy S(t) in Fouriertransformer 37 and also Fourier transforming the noise excited responseV(t) in Fourier transformer 38 and then complex multiplying the Fouriertransforms of the noise S(t) and'the resonance response V(t) in amultiplier 39 to obtain the Fourier transformed resonance line spectrumof the sample under analysis which is thence fed to the recorder 14 forrecording as a function of time or as a function of frequency to obtainan output spectrum of the sample under analysis. Complex multiplying asused herein is defined to mean multiplying of complex numbers. (SeeAdvanced Engineering Mathematics, C. R. Wylie Jr., McGraw-Hill 2ndEdition, l960, p.528).

In the spectrometer 36 for the case where the sequence generator 5 is ofa pseudorandom nature, i.e., repetitive, a multichannel storage andadder may be provided between the output the audio frequency amplifier 9and the input of the Fourier transformer 38 for repetitively samplingand accumulating the resonance response V(t) in respective channels ofthe storage and adder to obtain a time average of the noise excitedresponse V(t) which is then subsequently fed to the Fourier transformer38 to obtain a time averaged Fourier transformed output which iscross-correlated with the Fourier transform of the noise. The Fouriertransform of the noise will be the same for each cycle of thepseudorandom sequence. Thus, the Fourier transform of the pseudorandombinary sequence noise excitation S(t) need not be time averaged beforebeing fed to the multiplier 39 for multiplication with the time averagedoutput of the Fourier transformer 38.

As an alternative, the multi-channel storage and adder may be disposedat the output of complex multiplier 39; for a case where the sequencegenerator 5 produces a repetitive or pseudorandom sequence, forobtaining a time average of the resonance spectral data which may thenbe read out to the recorder 14. As in the spectrometer of FIG. 3 thenoise excitation S(t) may be obtained by field modulation as well asphase modulation of the transmitter signal.

Referring now to FIG. 5, there is shown an alternative spectrometer 42incorporating features of the present invention. The spectrometer 42 ofFIG. 5 is essentially the same as that previously described with regardto FIG. 4 and consists of a small general purpose computer of the type620 i with an 8,000 word memory manufactured by Varian Data Machines,Newport Beach, California. The interfaces between the computer 43 andthe spectrometer such as a Varian Associates type DA 60 spectrometermanufactured by Varian Associates, Palo Alto, California, is done by ageneral interface of the type S8100 which includes A to D and D to Aconverters, sense and control lines.

The 620 1' computer 43 generates a maximum length pseudorandom binarysequence utilizing the A register of the computer 43 as a shift registerwith 10 bits. One bit output of the A register of the computer 43 isused to set and reset a flip-flop register which feeds into the binaryphase modulator 4 which sets the phase of the RF transmitter signal to 0or r according to the state of the flip-flop. The modulated RF output isamplified in a power amplifier, not shown. An RF power of approximately50 milliwatts is employed to cover a spectral range of one kilohertz inthe 60 megacycle band. The noise excited resonance response V(t) ispicked up in the receiver coil within the probe 3, is amplified by RFamplifier 6, demodulated in RF phase detector 7 and fed through alowpass filter with a 3 db frequency of 0.4 to 2 kilohertz, depending onthe width of the spectrum. The audio output of the audio amplifier 9 isdigitized and stored either in the memory of the computer 43 or in atime averaging computer of the type C-l024 (Varian Associates) notshown. The sampling process, for a storage, is synchornized with theexciting sequence S(t) and produces 1,023 samples per period which areadded to the corresponding samples of the former priods, i.e., cycles ofthe pseudorandom binary sequence.

The signal processing and transformation are done after data collection.The Fourier transformed and cross-correlated output resonance linespectrum is fed through a digital-to-analog and thence to the XYrecorder 14.

The flow diagram of the computer program for data processing is shown inFIG. 6. The noise excited resonance response V(t) is base line correctedby subtraction of its average value to increase the accuracy of thefollowing fixed point operations. A conventional Fourier transformroutine is employed to transform the l,023 data points into 5 12 pair ofcomplex Fourier coefficients with IS bit accuracy. The Fouriercoefficients of the noise and resonance signals are multiplied by thecomplex conjugate Fourier coefficients of the shift register code usedfor noise excitation of resonance. This produces the complex spectrum.To obtain pure' absorption or a pure dispersion mode resonance line moderesonance line spectrum output, a phase correction routine is providedwhich allows variance of the phase of the spectrum by arbitrary anglesby a linear combination of real and imaginary parts of the complexspectrum. This type of correction routine is disclosed and claimed incopending U.S. application Ser. No. 16,497 filed Mar. 4, 1970, andassigned to the same assignee as the present invention.

It is, as well, possible to sample the signal by 1024 data points perperiod and subsequently to use the last Fourier transform routinedescribed by Cooley and Tuckey which considerably reduces computationtime. In this case, binary random sequence and coupling must besynchronized such that during 2-l basic skips of the random sequence 2"equidistant samples are taken (e.g. n=l0).

The synchronization could be effected as follows: Assuming that theperiod length T shall be 1 sec, the frequency of the basic clock withinthe arithmetic unit must be 2"(2"1) hertz which is divided by 2" in abinary counter within the arithmetic unit to generate the shift pulsesfor the binary pseudorandom noise generator formed by the A register. Atthe same time, the basic clock frequency is divided by 2"l using a shiftregister with n binaries and feedback sampling times for the adder.

Field-frequency control is added to the spectrometer 42 to obtain anenhanced stability of the output spectra by use of afield-frequencycontrol sample within the probe 3 and modulating the transmitter signalf, with an audio frequency derived from audio frequency oscillator 44and fed to balanced audio modulator 45 to produce a side band at theresonance frequency of the control sample. The control sample resonanceline output in the output of audio amplifier 9 is fed to one input of anaudio phase detector 46 for phase detecting with a sample of the audiomodulation signal derived from audio oscillator 44 to produce a DC errorsignal employed as a field-frequency control signal for superimposing acorrective magnetic field component H upon the polarizing magnetic fieldto sustain resonance of the control sample, thereby stabilizing thefieldfrequency parameters of the spectrometer.

Although the noise excited resonance apparatus of the present inventionhas been described, thus far, as it is applied to gyromagnetic resonancespectrometers,

particularly of the nuclear resonance types, this is not a requirementand the features of the present invention are applicable in general tospectrometers which include nuclear resonance spectrometers, electronspin spectrometers, nuclear quadrupole resonance spectrometers and maybe employed not only at radio frequencies but at microwave frequenciesas well. As an alternative to phase modulation of the radio frequencytransmitter signal f, the radio frequency transmitter signal may beintensity modulated with the pseudorandom binary sequence or with arandom binary sequence to produce noise excitation of the sample underanalysis.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a noise excited nuclear and electron resonance apparatus, meansfor irradiating a sample of matter under investigation with a spectrumof noise energy having sufficient bandwidth to cover a plurality ofresonance lines of the sample to be excited for exciting resonance ofplural resonance lines of the sample simultaneously, means for receivingthe simultaneously excited resonance lines signals emanating from thenoise excited sample, means for correlating the resonance exciting noiseenergy with the noise excited resonance line signals to derive across-correlation function, and means for Fourier analyzing thecrosscorrelation function to obtain resonance line informa tionconcerning the sample under analysis.

2. The apparatus of claim 1 wherein said means for irradiating thesample with a spectrum of noise energy includes means for irradiatingthe sample with radio frequency energy which is modulated with noiseenertiplying said resonance line signals by different time delayedrepresentations of said resonance exciting segarate one of said pluralitof channels.

. In a noise excited nuc ear and electron resonance apparatus, means forapplying a spectrum of noise energy to a sample of matter disposed in apolarizing magnetic field to excite simultaneously a spectrum ofresonance lines within the sample under analysis, means for receivingthe spectrum of resonance line signals simultaneously emanating from thesample, means for Fourier transforming a sample of the resonanceexciting noise energy applied to the sample to derive an exciting noisetransform function, and means for Fourier transforming the noise excitedresonance line spectrum emanating from the sample to derive a resonancetransform function, and means for complex multiplying the resonanceexciting noise transform function by the resonance transform function toobtain resonance line information concerning the sample under analysis.

6. The apparatus according to claim 5 wherein said means for irradiatingthe sample with a spectrum of noise energy includes means forirradiating the sample with radio frequency energy which is modulatedwith noise energy.

7. The apparatus of claim 5 wherein the sample is disposed in apolarizing magnetic field, and said means for irradiating the samplewith noise energy includes, means for irradiating the sample with radiofrequency energy, and means for modulating the intensity of thepolarizing magnetic field with the noise energy.

8. In a method for obtaining excited nuclear and electron resonanceinformation from a sample under analysis the steps of, irradiating thesample under investigation with a spectrum of noise energy having asufficient bandwidth to cover a plurality of the resonance lines of thesample to be excited for exciting resonance of plural resonance lines ofthe sample simultaneously, receiving the simultaneously excitedresonance lines signals emanating from the noise excited sample, andcorrelating the resonance exciting noise energy with the noise excitedresonance line signals to derive a cross-correlation function, andFourier analyzing the cross-correlation function to obtain resonanceline information concerning the sample under analysis.

9. In a method for obtaining noise excited nuclear and electronresonance information from a sample under analysis the steps of,applying a spectrum of noise energy to the sample of matter disposed ina polarizing magnetic field to excite simultaneously a spectrum ofresonance lines within the sample under analysis, receiving the spectrumof resonance line signals simultaneously emanating from the sample,Fourier transforming a sample of the resonance exciting noise energyapplied to the sample to derive an exciting noise transform function,Fourier transforming the noise excited resonance line spectrum emanatingfrom the sample to derive a resonance line transform function, andmultiplying the resonance exciting noise transform function by theresonance line transform function to obtain resonance line informationconcerning the sample under analysis.

' l i i i i

1. In a noise excited nuclear and electron resonance apparatus, meansfor irradiating a sample of matter under investigation with a spectrumof noise energy having sufficient bandwidth to cover a plurality ofresonance lines of the sample to be excited for exciting resonance ofplural resonance lines of the sample simultaneously, means for receivingthe simultaneously excited resonance lines signals emanating from thenoise excited sample, means for correlating the resonance exciting noiseenergy with the noise excited resonance line signals to derive acrosscorrelation function, and means for Fourier analyzing thecrosscorrelation function to obtain resonance line informationconcerning the sample under analysis.
 2. The apparatus of claim 1wherein said means for irradiating the sample with a spectrum of noiseenergy includes means for irradiating the sample with radio frequencyenergy which is modulated with noise energy.
 3. The apparatus of claim 2wherein the sample is disposed in a polarizing magnetic field and saidmeans for irradiating the sample with noise energy includes, means forirradiating the sample with radio frequency energy, and means formodulating the intensity of the polarizing magnetic field with noiseenergy.
 4. The apparatus of claim 3 wherein said means for correlatingthe resonance exciting noise energy with the noise excited energyresonance line siGnals comprises a plurality of channels forsimultaneously multiplying said resonance line signals by differenttime-delayed representations of said resonance exciting noise, each saiddifferent time-delayed representation being multiplied by said resonanceline signal in a separate one of said plurality of channels.
 5. In anoise excited nuclear and electron resonance apparatus, means forapplying a spectrum of noise energy to a sample of matter disposed in apolarizing magnetic field to excite simultaneously a spectrum ofresonance lines within the sample under analysis, means for receivingthe spectrum of resonance line signals simultaneously emanating from thesample, means for Fourier transforming a sample of the resonanceexciting noise energy applied to the sample to derive an exciting noisetransform function, and means for Fourier transforming the noise excitedresonance line spectrum emanating from the sample to derive a resonancetransform function, and means for complex multiplying the resonanceexciting noise transform function by the resonance transform function toobtain resonance line information concerning the sample under analysis.6. The apparatus according to claim 5 wherein said means for irradiatingthe sample with a spectrum of noise energy includes means forirradiating the sample with radio frequency energy which is modulatedwith noise energy.
 7. The apparatus of claim 5 wherein the sample isdisposed in a polarizing magnetic field, and said means for irradiatingthe sample with noise energy includes, means for irradiating the samplewith radio frequency energy, and means for modulating the intensity ofthe polarizing magnetic field with the noise energy.
 8. In a method forobtaining excited nuclear and electron resonance information from asample under analysis the steps of, irradiating the sample underinvestigation with a spectrum of noise energy having a sufficientbandwidth to cover a plurality of the resonance lines of the sample tobe excited for exciting resonance of plural resonance lines of thesample simultaneously, receiving the simultaneously excited resonancelines signals emanating from the noise excited sample, and correlatingthe resonance exciting noise energy with the noise excited resonanceline signals to derive a cross-correlation function, and Fourieranalyzing the cross-correlation function to obtain resonance lineinformation concerning the sample under analysis.
 9. In a method forobtaining noise excited nuclear and electron resonance information froma sample under analysis the steps of, applying a spectrum of noiseenergy to the sample of matter disposed in a polarizing magnetic fieldto excite simultaneously a spectrum of resonance lines within the sampleunder analysis, receiving the spectrum of resonance line signalssimultaneously emanating from the sample, Fourier transforming a sampleof the resonance exciting noise energy applied to the sample to derivean exciting noise transform function, Fourier transforming the noiseexcited resonance line spectrum emanating from the sample to derive aresonance line transform function, and multiplying the resonanceexciting noise transform function by the resonance line transformfunction to obtain resonance line information concerning the sampleunder analysis.